Signaling system for railroads



Sept. 8,1931. c. F. ESTWICK 1,822,572

SIGNALING SYSTEM FOR RATLROADS Filed July 12, 1929 3 Sheets-Sheet 1 FIG. 1.

L12 t l M T [Ma Transmission Line Transmission Line BY glfgNiOR a Sept. 8,1931. c. F. ESTWICK 1,822,572

SIGNALING SYSTEM FOR RAILROADS Filed July 12. 1929' 3 Sheets-Sheet 2 Sept. 8, 1931'. c. F. ESTWICK 2 SIGNALING SYSTEM FOR RAILROADS Filed July 12, 1929 3 Sheets-Sheet 3 FIG. 6.

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TI'ORNEY Patented Sept. 8 193i UNITED STATESuPATENT OFFICE CHARLES J3. ESTWICK, OF ROCHESTER, NEW YORK,ASSIGNOR TO GENERAL RAILWAY SIGNAL COMPANY, 'OF ROCHESTER, NEW YORK SIGNALING SYSTEM FOR RAILROADS,

Application filed July 12, 1929. Serial 110.877,?13.

This invention relates to railroad signaling track circuits and more particularly to alternating current track circuits including two element track relays.

Alternating current track circuits, including two element track relays, have many applications, as the local windings ofsuch relays furnish the greater part of the electrical energy, while the track phase windings mere- 10 ly furnish enough energy at a given angle of phase displacement to produce the required torque for controlling the contacts of the track relay. Such an alternating current track circuit may be extremely long as compared to direct current track circuits due to the small amount of electrical energy neces-.

sary to be supplied to the track phase winding by the track circuits with which it is associated.

As the length of an alternating current track circuit increases, the phase angle of the lagging current in the track phase winding increases correspondingly in respect to the voltage supplied bythe transmission line, which may be used as a reference. This phase angle of the track phase current is not determined by the inductance of the circuit alone, but is also dependent upon the resist ance of the infinite number of leakage paths provided through the ballast, which leakage paths or circuits are in multiple .with the track rails. These conditions being true, if the track circuit is long enough and the ballast resistance is low, the vector of the ourrent in the track phase winding of a partic ular track circuit may fall within any one of the four quadrants of a vector diagram...

However, with track circuits of practical length and practical ballast conditions, the track phase current seldom lags its voltage reference more than 180,but if the leads of the track phase winding be reversed,thecurrent vector may still fall in the remaining quadrants. Thus, with this wide variation in phase angle for the lagging track phase winding current, it has been difiicult to obtain the proper phase relation between the currents in the track phase and local phase windings in order to maintain the desired torque and shunting characteristics of the track relay.

It is the purpose of the present invention toset forth a method and means for regulating the phase displacement between the track phase Winding and the local phase winding of two element track relays, so that any time the phase displacement can be adjusted to give a maximum amount of torque. Also, the present invention contemplates the use of certain peculiarities of the phase relations of the track phase winding and of the local phase winding of a two element track relay during shunting to produce a maximum shunting efficiency. In other words, a means is to be set forth and a method explained whereby a two element trackrelay may be deenergized by a shunt having a much greater value of resistance than is the usual practice, due to the phase displace ments as obtained by the adjusting means and method of adjustment to be set forth.

The present invention, in giving better shunting elliciency, gives a greaterassurance of operation of the track relay under both 75 wet and dry weather conditions. Also, as the adjusting means is preferably provided at the location of the track relay, a most convenient means for adjusting and checking the operation of the track relayis thus provided.

.Other objects, purposes and characteristic features will inpart be pointed out and in part be obvious, as a description of the invention is set forth in connection with the accompanying drawings.

In describing the invention in detail, reference will be made to the accompanying drawings, in which Fig. 1 shows an alternating currenttrack circuit as used in general practice;

Fig. 2 shows an alternating current track circuit as included in the present invention;

Fig. 3 shows a vector diagram explanatory of Fig. 1; p I

Fig. 4 shows a vector diagram explanatory of an ideal modification of Fig. 1';

Fig.5 shows a vector diagram explanatory of Fig. 2; I

Fig. 6 shows a modification of connections 100 for a two element track relay in accordance with the present invention;

Fig. 7 showsa second modification of connections for a two element track relay in accordance with the present invention;

Fig. 8 shows a third modification of con nections tor a two element track relay in accordance with the present invention.

Referring now to the drawings, Fig. 1 shows an alternating current track circuit having a track transformerl. with its primary winding connected to a transmission line and with its secondary winding connected to a track section TK through a variable limiting reactance LR connected in series. A track relay TB is also shown connected to the track section TX at the extreme end from the track transformer T, and associated wit-l1 said relay TR is a local phase winding LO connected to said t*ansn1ission line through a local transformer T lVith reference to Fig. 3, let us assume that the voltage applied by the transformer T, is represented by the vector E, and that the current flowing in the track phase winding of the track relay TR is represented by the vector TR. As a shunt, having a given n1aximum value of resistance, which, when placed across the track rails at the relay end of the track section, will drop the contacts of said track relay, the current in the track phase winding of relay TR assumes a value and phase relation represented by the vector TR". A circle I may now be constructed with its circumference including the origin O of the vector diagram and the extreme points of the vectors TR and TR". The circumference of the circle P, defines the limits of the current values for other of shunting resistances,

. placed across the track rails at a particular point at the relay end of the track circuit.

The current during wet weather conditions is represented by the vertor TR \Vhen said relay TB is shunted during wet weather conditions, the current in the track phase winding assumes a value TR which together with TH and the origin 0 define, and of course tall upon, another circle similar to the circle P, but not shown for the sake of clearness. It is thus seen, that the vector representing the values of current when the relay is shunted, rotates in a clock-wise direction about the origin 0 oi the vector diagram.

As the transnnssion line furnishes power 1! i 4.1 f i 1 T 1 T1 t1 7 1t iOl both one t1 ans oimei ant 1e \0 age vector E will also serve as a reference for the current vector LO representing the current in the local winding LO of the track relay TR. The torque produced for causing the contacts of relay TR to assume energized position is proportional to the values of current flowing 1n the local phase winding L0 and 111 the track phase w1nd1ng and directly proportional to the sine of the angle of displacement between the vectors representing the currents, as for example the vectors L0 and TR, values for dry weather conditions. To cause the contacts of relay TR to assume deenergized positions, it is necessary to place a. shunt of not more than a given maximum resistance across the track rails at the relay end of the track section to reduce the track phase current to a value TR. However, as the vector representing the track phase current rotates in a cloclewise direction, the sine of the displacement angle increases at the same time that the current TR" decreases so that the resistance. value of the shunt to pro duce a dropping away ot' the contacts of relay TR must be considerably smaller than it the vector TR did not so rotate. v

In accordance with the present invention, it is proposed to take advantage of the retation of the track phase current when shunted, so that it will not be necessary to have a shunt of such a low resistance value to produce a dropping away of the contacts of relay TR. Let us arbitrarily place the vector LO as shown in Fig. at, so that the local phase current LO lags the track-phase current TR by the same angular displacement that it leads the track phase current in Fig. 3. In this case it is found, that the current, which flows in the track phase winding when the relay TR is shunted, assumes a value TR. This current value TR (see Fig. i) is about 200 percent greater than the value TR (see Fig. 3), which value TR is obtained by a maximum shunting resistance of approximately 200 percent greater resistance than used to obtain the value TR.

In accordance with the present invention, means for adjusting the phase displacement between the current in the track phase winding and the local phase winding of the track relay TB, is furnished by a variable condenser C and an adjustable reactance RE as illustrated in Fig. 2, in which a variable limiting resistance LR? is substituted for the limiting reactance LR of Fig. 1.

With the condenser C and the reactance RE connected as is obvious from the drawing, it is possible to easily obtain an adjustment of the phase angle oi the local phase current in respect to the voltage of the transformer T from its normal angle up to an angle of 180 degrees. Thus, it is seen that if the leads of the local phase winding are reversed, it is further possible with'the same apparatus to obtain adjustment of phase relationship through a similar angle placed diametrically opposite.

It is to be noted here, that the use of a limiting resistance LE in place of a limit ng re'a'ctance causes a very much smaller lag in the phase of the current in the track phase windings of track relay TR, so that for this particular case the results obtained with the arrangement as shown in Fig. 2 are set forth in Fig. 5, in which the various current values fall within the fourth quadrant of the vector diagram. 7

WVith reference to Fig. 5, the vector TR represents the current in the track phase winding during dry weather conditions, the vector TR represents the current in the track phase winding during wet weather conditions, the vector TR represents the current in the track phase winding during shunting with dry weather conditions, the vector TR represents the current in the track phase winding during shunting with wet weather conditions and the vector LO represents the current in the local phase winding of the relay TR.

The results obtained by actual experiment as shown in Figs. 3 and 5, have proventhat the value of the maximum shunting resistance, at the relay end of the track .circuit, for wet weather conditions (see Fig. 5) is about 463 percent greater than the value which would be encountered if the arrangement as shown in Fig. l were used, while with dry weather conditions, the value of maximum shunting resistance is about 144 percent greater than with the arrangement used in Fig. 1. It is also pointed out, that as the angle of displacement between the local phase cur *ent and the track phase current decreases the maximum shunting resistance value increases. However, in practice it would probably not be advisable to adjust the phase displacement for this maximum usable value of shunting resistance during dry weather conditions as the wet weather conditions would alter the adjustment to cause the track phase vector to rotate beyond the local phase vector, so that the local phase vector would be in a leading position as set forth in explanation of Figs. 1 and 3, also, in the case of a three position relay, such a phase reversal would cause a false indication.

It will be stated here that the conclusions drawn in the preceding paragraph are the result of actual data taken by the inventor. In Fig. 3 the results of the experimental data show vectorially the current value obtained. According to the dataobtained the value of resistance required to reduce the relay track phase winding current TR to the value represented by vector TR equals 0.34 ohms, while the value of resistance necessary to reduce the current represented by vector TR to the valve represented by vector TR equals 0.60 ohms. In Fig. 5 the data obtained under experiments according to the present invention, show the current values obtained vectorially, in which data it was found that a resistance of 0.49 ohms was necessary to reduce the current value represented by vector TR? to the value T11 while a resistance of 9.78 ohms was necessary to reduce the current value represented by vector TR to a value TR It is of course understood that with the same pieces of apparatus having like reference characters. These various modifications give desirable phase adjustment for the local phase circuit in a manner similar to that obtained with the circuit arrangement shown in Fig. 2, with each modification having certain. characteristic points of utility in obtaining this desired result.

Fi 6 shows one modification of circuits for a relay having two local windings LO and LO inductivelyassociated with each other. I

The local winding L0 is connected in series with the variable reactance RE to the secondary winding of the transformer T while the local winding L0 is shunted by the condenser C. This arrangement may be designed so that the capacity of the condenser C may be much smaller than in the circuit arrangement shown in Fig. 2, as the resultant capacity effect of the condenser O as transmitted to the circuit including the local winding L0 is inversely proportional to the square of the ratio of turns between the two windings L0 and L0 Such an arrangement is peculiarly adaptable to the vane type of relay where two local windings are easily incorporated.

Fig. 7 shows a second modification, where the principle of using inductive coupling to reduce the capacity of the condenser C is applied to a relay having but one local winding LO. A transformer T has its primary winding connected across the local winding L0 and has its secondary winding shunted by the variable condenser (1' The multiple combination of the local winding L0 and primary winding" of the transformer T is connected in series with the variablereactance RE to the secondary of the transformer T Fig. 8 shows a third modification, wherein a fixed resistance R is used in parallel'with the local winding LO ofthe track relay TR. This multiple combination is connected in series with the variable reactance RE to the I secondary of the transformerT The main advantage of this modification is that the necessary adjustment in particular casesmay be obtained without the use of a condenser.

It will be noted that with this arrangement, it is possible to obtain an adjustment of the phase angle of the local phase current in respect to the voltage of the transformer T from its normal. angle up to an angle of approximately 110 degrees and by reversal of the leads, it is further possible to obtain an adjustment of phase relationship through such an angle in phase diametrically opposite.

Various means have thus been set forth for regulating the angle of phase displacement between the currents in the local and the track windings of a two element track relay. It has been further shown how this adjustable means may be used to adjust the phase relationships in such a manner as to take advantage of an inherent characteristic of a shunted track section using alternating current for signal purposes.

It is of course understood that the same results could be obtained by adjusting the track phase in relation to the local phase. However, as the procedure is the same, as above, it is not deemed necessary to set forth. means whereby this may be accomplished.

The present invention having been shown and described in connection with rather specilic circuits and devices, it should of course be understood that the various means shown and described are capable of certain modifications and rearrangen'ients without departing from the spirit or scope of the present invention as defined by the appended claims.

lVhat I claim is 1. The method, in connection with a track relay having a track phase and a local phase and employed in a track circuit, for iniproving the relay response to shunting, comprising adjusting the two phase circuits relatively to each other so that the track phase current leads the local phase current under unshunted conditions.

2. The method, in connection with a tracl; relay having a track phase and a local phase and employed in a track circuit, "for improving the relay response to shunting, comprising adjusting the twophase circuits relatively to each other so that the track phase current leads the local phase current by an angle not greater than approximately 90 degrees, or such angle plus 180, whereby shunting of the relay not only decreases the value of the track phase current but also brings it more nearly into phase with the coacting local phase current.

In combination, a track circuit including an alternating current relay having a track phase winding and a local phase winding, and means relatively varying the con stants oi the phase circuits to cause the local phase current to lag the track phase current under unshunted conditions.

l. In combination, an alternating current track relay having a track phase wi ding and a. local phase winding, :1 track circ t including said track phase winding of said alternating current track relay, and means relatively varying the constants of the phase windings to cause the local phase current to lag the tra ck phase current under unshunted conditions.

reeasvs 5. In combination, an alternating current track relay having a track phase winding and a local phase winding, a source of alternating current potential, a track circuit ineluding said track phase winding of said alternating current track relay and said source of alternating current potential, a local phase circuit including said local phase winding of said alternating current track relay and said source of alternating current potential, and means varying the constants of said local phase circuit to cause the local phase current to lag the track phase current by an angle not greater than approximately 90 degrees under unshunted conditions.

6. In combination, an alternating current track relay having a track phase winding and a local phase winding, a source of alternating current potential, a track circuit including said track phase winding of said alternating current track relay and said source of alternating current potential, a local phase circuit including said local phase winding of said alternating track relay and said source of alternating current potential, and means varying the constants of said local phase circuit to cause the local phase current to lag the track phase current by an angle of such value, under unshunted conditions, as to allow a shunt of maximum resistance to produce shunting conditions.

7. In combination, an alternating current track relay having a track phase winding and a local phase winding, a source of alternating current potential, a track circuit including said track phase winding 01' said alternating current track relay and said source of alteu nating current potential, a local phase circuit including said local phase winding of said alternating current track relay and said source of alternating current potential and means varying the constants of said local phase circuit to cause the local phase current to lag the track phase current with said means including a variable condenser shunted across said local winding and a variable reactance connected in series with said local. phase winding shunted by said variable condenser and said source of alternating current potential.

8. In combination, an alternating current track relay having a track phase winding and two local phase windings, a source of alternating current potential, a track circuit including said track phase winding 01 said alternating current track relay and said source of alternating current potential, two local phase circuits inductively associated with each other, and means varying the coin stunts oll both of said local phase circuits to cause the currents of the local phases to lag the track phase current with said means including a variable condenser shunted across one of said local windings, and a variable reactance connected in series with the other of said local windings and said alternating current potential source.

9. In combination, an alternating current track relay having a track phase winding and a local phase winding, a source of alternating current potential, a track circuit including said track phase winding of said alternating current track relay and said source of alternating current potential, a local phase circuit including said local phase winding of said alternating current track relay and said source of alternating current potential, and means varying the constants of said local phase circuit to cause the local phase current to lag the track phase current with said means including a transformer with its primary winding connected in multiple with said local phase winding of said alternating current track relay, a variable condenser shunted across the secondary winding of said transformer, a variable reactance connected in series with said local winding and said primary of said transformer connected inmultiple, and said source of alternating current potential.

10. The method, in connection with a track relay having a track phase and a local phase and employed in a track circuit, of adjusting the phase relation of the current in the track phase winding to the current in the 10 cal phase winding, so that the application of a shunt across the track rails of the trackcircuit, regardless of the length, at any position on the track, will cause a decrease in the sine of the angle of phase displacement between the currents in the respective phase windings.

11. The method, in connection with a track relay having a track phase and a local phase and employed in a track circuit, of adjusting the phase relation of the current in the track phase winding and the current in the local phase winding, so that the application of a shunt across the track rails of the track circuit, regardless of length, at any position on the track, will cause a change so that variation of phase displacement will be favorable for reducing the torque in the relay.

12. A system, in connection with an alternating current track circuit including a track relay having a track phase and a local phase, of adjusting the phase relation between the track phase current and the local phase current relative to each other so that the application of a shunt across the track rails of the track circuit at any point on the track regardless of the distance between the track relay and its alternating current source, will cause a decrease in the arithmetical Value of the sine of the angle of phase displacement between the currents in the track phase winding and the local phase winding.

In testimony whereof I aflix my signature CHARLES F. ESTWIGK. 

